I was wondering if anyone knows of any good tutorials on how to use Caustics... in Mental Ray for Maya 4.5?

Ed

Nicool

03-06-2003, 08:48 PM

There exists an advanced one, but you can use the "simple" maya caustic plugin too;)

stunndman

03-06-2003, 09:02 PM

AW is hosting a short video tutorial on caustics in MR

and there some on the net - browse through the end of the sticky faq thread - the link should be there

alexx

03-06-2003, 09:05 PM

if you stumble across the one that has rthe volumetric caustics in it: forget it.. it is way advanced and not explained in any way and anyway stolen from a book about mental ray :)

cheers

alexx

FlexGiddy

03-11-2003, 07:54 PM

Haha I figured it out.....Well I now have another problem....lets say I make a poly sphere....and I apply a glass shader to it..I used the True Glass Shader off of highend3d...so others can use the same shader.....well when I render it. there is a grid reflecting in the glass ball....what is that...? Anyone know?

Ed

Swami Gattas

03-17-2003, 09:58 PM

Check your shader in Hypershade, it might have an environment attached to it that is the grid you see reflected...

just a thought...

LowEndFrequency

03-18-2003, 02:29 AM

Yeah that shader has an environment map on it, I was havin that problem too.

FlexGiddy

03-18-2003, 05:43 PM

Okay thank you guys I was able to solve that probem…..(I made my own shader)...here's another question though....I went to ww.aliaswavefront.com and I made a glass shader from the tutorial on the site, and for some reason I get this really hard shadow when I raytrace....even when I download their sample file and I apply my glass shader to their vase and not change anything else.......Why!?!?!?!?!? :annoyed: Blasted thing!! But I can't help but experiment (sigh)...... :rolleyes:

I dont' have a a problem there...raytrace is on everywhere.... default render globals, mental ray render globals, and on the lights.......I just don't understand what's up......

Flex

Swami Gattas

03-18-2003, 10:24 PM

So which one are you rendering with then?
MR or plain Maya Renderer? something's up with how your shader is handling shadows or one of your lights isn't obeying a flag... are you using linked lights? I dunno it could be many things :P

if its transparent you need raytrace shadows to get that see through shadow effect expected in real glass, if you-re using MR I think there's settings for the raytracing and caustics that might also help... I haven't really played with MR yet :P

Also sometimes you need to save your scene and restart cause maya can get cranky lol

Swami Gattas

03-18-2003, 10:40 PM

oh I just remembered that sometimes you need to tweak photon emition so that you can get detail in caustics...

Just a thought...

LowEndFrequency

03-18-2003, 11:20 PM

X-tender hooked me up with this link in another thread. It really cleared up alot of caustics questions I was having, and there is a good section on Global Illumination as well.

http://www.3dluvr.com/intercepto/maya_tuto.htm

X-Tender

03-18-2003, 11:25 PM

=D .. my Caustic test!

http://xtender.00network.org/forum/glas.jpg

Swami Gattas

03-19-2003, 02:31 AM

That's awesome! I'll check that link out too, maybe I can get into caustics too tho I really hate how long it takes to render when you switchit on :P

FlexGiddy

03-19-2003, 07:34 AM

Now that type of render is what I'm trying to do.....I'm trying out the suggestions right now so I'll post some renders as soon as I can.....If needed I could post some of the old stuff if that'll help....? I'm not sure... Let me know.

Flex

That is a sweet render.....wow

X-Tender

03-19-2003, 07:54 AM

Originally posted by Swami Gattas
I really hate how long it takes to render when you switchit on :P

i needed 'bout 4 minutes to render the pic in 1024x768 ;)

FlexGiddy

03-19-2003, 08:30 AM

Originally posted by X-Tender
i needed 'bout 4 minutes to render the pic in 1024x768 ;)

What..?!?!?!? How...??

Flex

X-Tender

03-19-2003, 09:26 AM

;) ... its important taht you set the min and max aradius by final gather .. without the values it takes much longer ...

FlexGiddy

03-19-2003, 05:09 PM

Dang...I wish I knew that before....:rolleyes: But okay I"m going to pop off a few renders then and post.

Flex

Swami Gattas

03-19-2003, 05:20 PM

Damn! 4 minutes? That IS fast!! :P
Maybe you should do a tutorial on caustic rendering for us less fortunate *hint* *hint* lol

X-Tender

03-19-2003, 06:01 PM

hey i'am still a render noob =) .. jstu read the tutorials on the page i've posted there is evertyhin i know =)

FlexGiddy

03-19-2003, 06:49 PM

I set my min and max aradius in Final Gather to 5 and 50.....Is that even close to being correct...?

Flex

X-Tender

03-19-2003, 07:17 PM

well i use abaout 0.6 min and 8 max =) ...

FlexGiddy

03-20-2003, 07:58 PM

Ahh okay.....:thumbsup:

Flex

LowEndFrequency

03-20-2003, 10:05 PM

Also make sure you aren't using a point light, as was my mistake. A point light emits photons in every direction while a spotlight will emit the same amount of photons but concentrated into a space the size of your render.

The result: Higher quality caustics with lower render times.

LowEndFrequency

03-20-2003, 10:15 PM

Here is an example with a spotlight emitting 15,000 photons. This image took 10 minutes to render (20 seconds to emit photons, the rest mostly because of the glass and raytracing).

Before I had a point light and it took over an hour to render (mostly photon emission) and needed 5,000,000 photons to achieve the same quality caustics.

http://www.angelicglow.com/lowend/glass1.jpg

X-Tender

03-20-2003, 10:25 PM

looks nice .. i see you use arelight for your spotlight .. set the sampling values higher then you get a cleaner shadow .. without the noise ;) :thumbsup:

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